1. Field of the Invention
This invention relates to a new and improved tower structure, and more particularly, to a new and improved antenna and communications tower structure which is characterized by great strength and rigidity and which may be self-supporting. The tower includes a first set of outside legs arranged in a generally triangular configuration and a corresponding set of inside legs also disposed in a triangular configuration and positioned adjacent the outside legs in coaxial relationship. The inside legs are maintained in rigid alignment with the outside legs of the tower by means of a plurality of horizontally disposed collars positioned in spaced relationship along a substantial portion of the entire height of the tower, and carrying the inside legs and outside legs by means of leg flanges and flange bolts. The improved tower of this invention is characterized by great structural strength and rigidity since it is constructed in the shape of a pair of concentrically and coaxially disposed triangles, and is securely mounted in the earth. Both the outside legs and the inside legs of the tower are braced by means of horizontal braces fastened in spaced relationship to the outside and inside legs, respectively, and both the outside and inside legs are preferably encased in concrete to a selected depth at the base of the tower in order to insure the desired rigidity and strength.
2. Description of the Prior Art
Heretofore, various tower structures exhibiting a wide variety of functions and design choices have been used in the prior art. Typical of the early prior art towers is the structure illustrated in U.S. Pat. No. 296,375 to J. S. and F. U. Adams, which tower is characterized by a steel frame shaped generally in the form of double, offset hexagons, and further including a pair of concentrically disposed triangular shaped frames in the center thereof. Referring to FIG. 5 of the Adams drawing, the cross-sectional configuration of the tower is illustrated and reflects early attempts to achieve structural rigidity through the use of multiple geometric patterns known to have substantial strength.
U.S. Pat. No. 2,116,368 To E. J. Staubitz is characteristic of later tower structures, and discloses an antenna tower having a generally triangular shaped external frame with an inner structure also triangular in shape with the points of the inner triangle coinciding with the centers of the legs of the outer triangle, as illustrated in FIG. 2 of the Staubitz drawing. As further illustrated in the Staubitz drawing, the antenna tower was generally designed to be provided with guys, (reference numerals 10 and 15 in FIG. 1) and is provided with a generally narrow base, as further illustrated in FIG. 3.
Another such tower of later design is illustrated in U.S. Pat. No. 2,945,231 to M. W. Scheldorf, which tower is designed to serve as a communications antenna and is characterized by a generally triangular-shaped cross section having a coaxial inner triangular-shaped cross section, as illustrated in FIG. 3 of the drawing. The inner structure serves as the primary structural member of the antenna while the outer members characterize the suppressor structure. The legs of the tower are designed to be securely anchored in concrete for maximum rigidity and the triangular cross-sectional configuration of the structure insures maximum strength.
An inherent problem in the design of tower structures, and particularly tall tower structures designed to facilitate communication over a large geographical area, is the tendency of such structures to lean, bend and even break under the influence of wind load. Such towers are generally shaped in the form of a triangle in cross-section, since this geometric configuration has proved to be one of the strongest known shapes for tower design. It is apparent that the taller that these towers are built, the greater is the tendency of the tower to bend and ultimately fail under the influence of wind loading. Accordingly, an ideal design for a tower is one which incorporates extreme rigidity and strength from the base to the top in order to provide maximum stability against wind load.
It is therefore an object of this invention to provide a new and improved tower of generally triangular cross-sectional configuration which may be used for communication and other purposes, and which is characterized by great strength and rigidity.
Another object of the invention is to provide a new and improved tower structure, the cross-section of which generally comprises a pair of coaxial triangles with corresponding apexes formed by a set of three outer legs and a set of three inner legs and stabilized by a plurality of collars positioned in spaced relationship along a substantial portion of the length of the tower.
Yet another object of the invention is to provide a new and improved tower structure of great strength and rigidity which is characterized by a first set of three outside legs disposed in a generally triangular configuration and a second set of three inner legs also disposed in generally triangular configuration and corresponding in coaxial, adjacent relationship to the outside legs, respectively, with the legs forming adjacent apexes of the outer and inner triangles, and held securely and rigidly in position by a plurality of collars positioned in spaced relationship along at least a portion of the height of the tower.
A further object of this invention is to provide a self-supporting tower structure characterized by a set of vertically oriented outside legs and a set of vertically oriented inside legs, each of which sets are disposed in a generally triangular configuration and are fitted with several collars and a plurality of braces to impart maximum stability and rigidity to the tower structure.
Yet another object of the invention is to provide a new and improved communications tower formed of a set of three outside legs and a set of three inside legs in the configuration of a pair of concentric and coaxial triangles, each of the legs being braced with the respective adjacent legs of its set and held securely in proper relationship by multiple collars, the legs also being mounted securely in concrete for maximum rigidity.
A still further object of this invention is to provide an improved tower structure which is characterized by a first set of three outside legs disposed in the configuration of an equilateral triangle, and a second set of three inside legs also disposed in the configuration of an equilateral triangle, with each of the legs forming an apex of the respective triangles, and each of the inside legs being disposed adjacent a corresponding one of the outside legs perpendicular to a line bisecting corresponding apexes and corresponding sides of the triangles opposite the apexes, the legs held securely and rigidly in place by collars positioned in spaced relationship along at least a portion of the height of the tower.